Density functional study of 19F chemical shielding tensors:: a systematic investigation with respect to basis sets and hybrid functionals

The F-19 shielding tensors of HF, CH3F, CHF3, NF3, SiF4, POF3, F-2, OF2, SiF2 and SF2 were calculated by DFT-GIAO methods. Acceptable basis set convergence and agreement with experimental data were found for the first six compounds. The performances of the BILYP, B3LYP, B3PW91 and MPW1PW91 hybrid functionals are equally satisfactory, while the G96LYP functional produces poor results in most cases. The optimum DFT level for F-19 shielding tensor calculations is found to be MPW1PW91/tzv2d1f. For the molecules F-2, OF2, SiF2 and SF2, the results are less satisfactory and sizeable deviations from experimental data are observed. It appears that DFT calculations of F-19 shielding tensors are less suited for these compounds at the present level of sophistication. (C) 2001 Elsevier Science B.V. All rights reserved.